The present invention relates to a proportioning chamber/dispenser fixture for storage vessels, more particularly for sliding control valves unitized with a proportioning chamber housing, by means of which input-side and output-side openings can be closed alternatively be closed.
As an example, these arrangements are preferably used in beverage dispensers, by means of which carbonated water is mixed with beverage concentrates for a refreshment drink. Storage vessels for the beverage concentrates are usually fabricated from a dimensionallly stable and gas-tight material, and are shaped like a bottle or cuboid. When installed in a beverage dispenser, these storage vessels are positioned with their discharge opening downward. Attached to this discharge opening is a proportioning chamber/dispenser fixture with input side and output-side discharge openings that can be closed alternately by means of a sliding control valve. The liquid (beverage concentrate) flows by gravity from the storage vessel into the proportioning chamber/dispenser fixture, when that fixture's input-side discharge opening is opened. When this input-side discharge opening is closed by the sliding control valve and, at the same time, the output-side discharge opening is opened, the liquid--likewise by gravity--emerges from the proportioning system, so that the quantity of liquid is essentially determined by the proportioning-chamber capacity.
In the prior art proportioning chamber/dispenser fixtures, however, leakage between the sliding control valve and the proportioning-chamber housing can influences the quantity dispensed in a manner difficult to control. Design of a guideway between the sliding control valve and the proportioning-chamber housing, which is as free of gaps as possible to avoid these leakages, is highly problematical, since this sliding control valve is supposed to be axially movable with the greatest possible ease inside the proportioning-chamber housing, so it can be reliably adjusted, in the form of a solenoid plunger, by an electrically generated magnetic field. This method of adjustment requires no mechanical linkages, so that replacement of the proportioning chamber/dispenser fixtures in the beverage dispenser, together with the storage vessels, can be carried out with ease.
It is possible to ventilate the head room of this storage vessel or a buffer space therewithin (DE OS No. 25 44 671) in order to ensure that the flow of liquid is not hampered by volume-equalizing air counterflows and by the subatmospheric pressure developing. These measures require additional technical effort, yet they have not proven to be advantageous, since the air in the head room of the storage vessel easily escapes therefrom to enter the head room of the storage vessel during the flow of the liquid. In the prior art systems, it has even turned out to be expedient to cause a build-up of subatmospheric pressure in the head room so as to counteract the leakage flows between the metering plunger and the wall of the proportioning-chamber housing. However, the pressure in a dimensionally stable storage vessel is dependent on external influences, especially on the response to temperature changes during intermittent cooling.